Mac upgrade specialist Sonnet has launched a range of replacement batteries for old iPods.

The company is offering new power cells for first-, second-, third- and fourth-generation iPods, and the iPod Mini. Battery technology has come on so far since these models were released that the new batteries provide significantly higher capacities yet are the same size as the originals. Sonnet said the cells offer 20-78 per cent more run-time than the old ones, depending on which model of iPod you own.

The first- and second-generation iPods, and Mini come out best, with 78 per cent 50 per cent capacity gains, respectively.

Sonnet's not the first to market with products like these - Newer Technology has been offering its NuPower line of replacement iPod batteries offering comparable capacity improvements for some months now, for example.

Both companies bundles iPod case-opening tools and full instructions with the new batteries, but Sonnet has upped the ante with a bundled installation video on CD.

Sonnet's first/second-generation upgrade battery costs $40/£24, while batteries for third- and fourth-generation iPods, and iPod Minis, cost $30/£20. They're all available in the US now, and will be coming to the UK later this month, Sonnet said. ®